1. Field of the Invention
The present invention relates to self-emitting type video signal processing devices that emit light themselves and that have a display screen that permits light adjustment.
2. Description of the Related Art
Recently there has been a demand for high-quality display devices, and one important element of such display devices is the brightness of their display screen. However, simply increasing the brightness of the display screen that is displayed on the display device requires a large consumption of power.
On the other hand, there is increased concern for the environment in recent years, and this has made it important to reduce power use.
It would be desirable to achieve a display device that can balance these opposing goals of increasing the brightness of the display screen and reducing power use.
To suppress power use, many self-emitting display devices have a control to restrict the power use when the video signal has a high average picture level (hereinafter, APL). When this control is active, control is performed such that the total light that is emitted by the display screen of the self-emitting display device is constant.
Accordingly, one technology for self-emitting display devices involves lowering the emission amount in parts of the display screen that viewers are relatively less likely to notice and increasing the emission amount at the display screen center, which viewers are more likely to focus on, by this amount that the emission has been lowered, so as to increase the overall sense of brightness of the display screen while keep a constant power consumption (for example, see JP H6-282241A, JP 2002-116728A and JP 2006-228199A).
FIG. 16 shows the configuration of a video signal display device 1600, which serves as an example of the conventional technology.
The video signal display device 1600 is made from a video signal processing device 1601 for performing predetermined processing on a video signal, and a display device 1602 that displays the video signal that has been processed by the video signal processing device 1601.
The video signal processing device 1601 is constituted by a mean luminance detection portion 1603 for detecting the APL of the video signal that is input, a gain creation portion 1604 for creating a gain for signal level adjustment based on the APL that has been detected, and a signal level adjustment portion 1605 for adjusting the signal level of the video signal that has been input based on the gain for signal level adjustment that has been created and outputting it to the display device 1602.
The operation of the video signal display device 1600 is described next using FIG. 16.
This explanation is made with regard to an example in which a video signal that forms an image such as that shown in FIG. 16B has been input to the video signal display device 1600, and the video signal forms the line between P and Q that is shown in FIG. 16B.
In this case, the signal level of the video signal that has been input is adjusted with the signal level adjustment gain based on the APL that has been detected by the mean luminance detection portion 1603, and the result is output to the display device 1602. Specifically, a signal level adjustment gain such as that shown in FIG. 16C is created for the video signal between P and Q, and the signal level of the video signal is adjusted by multiplying this signal level adjustment gain and the video signal between P and Q that has been input.
Thus, the signal level of the video signal that is output to the display device 1602 is higher near its center than at its periphery, and thus the display screen that is displayed on the display device 1602 is bright near the center between P and Q and becomes progressively less bright toward its periphery. Consequently, the video signal display device 1600 allows power usage to be lowered while preventing a drop in the display quality of the display screen.
With conventional video signal display devices, however, there is the problem that, because the emission amount is monotonically lowered from a certain point (for example, the display screen center) on the display screen of the video being displayed toward its periphery, if the display screen includes a plurality of regions that viewers readily focus on (such as faces), then correction by monotically decreasing the emission amount from the center of the display screen toward its periphery cannot always raise the emission amount in regions that are noticed, and it may not be possible to obtain a sufficiently bright feeling on the display screen.
The present invention was arrived at in light of these issues, and it is an object thereof to achieve a video signal display device, a video signal processing device, a video signal processing method, an integrated circuit, and a video signal processing program that can obtain a sufficient sense of brightness on the display screen, even if the display screen includes a plurality of regions that viewers a likely to focus on, and that also can suppress power usage.